Advertisements
Advertisements
प्रश्न
Define calcination.
उत्तर
If an ore is a carbonate or a hydrated oxide, it is heated in the absence of air to a temperature that is high but insufficient to melt the ore. The process is known as calcination.
APPEARS IN
संबंधित प्रश्न
Which metal becomes black in the presence of hydrogen sulphide gas in air?
Which metal is extracted from bauxite ore?
Which of the following metals can be obtained from haematite ore?
(a) copper
(b) sodium
(c) zinc
(d) iron
State one observation for each of the following :
Copper sulphate solution is electrolysed using copper electrodes.
Give the chemical formula of :
Cryolite
Answer the following questions based on the extraction of aluminium from alumina by Hall - Heroult’s Process :
Why is powdered coke sprinkled on top of the electrolyte?
Compare the properties of a typical metal and a non- metal on the basis of the following:
(a) electronic configuration
(b) nature of oxides
(c) oxidizing or reducing action
(d) conductivity of heat and electricity
Gold and silver are active metals.
Explain concept with example/explain with the help of a balanced equation.
Roasting
Answer the questions on the following passage.
The minerals from which the metal can be separated economically are called ores. Ores contain many types of impurities such as soil, sand and rocky substances along with metal compounds. These impurities are called gangue.
Metals can be extracted from their ores by means of various methods of separation. The process of extraction of metal in a pure state from the ores is also a part of metallurgy.
Ores are taken out from the mines and the gangue is usually separated from the ore at the site itself by various methods. Then the ores are carried out to the place where metals are produced. Here metals are extracted in pure form. Then metals are further purified by different methods of purification. This entire process is called metallurgy. Most metals being reactive do not occur in nature in the free state but are found in combined state as their salts such as oxides, carbonates, sulphides, and nitrates. however, the most unreactive metals that are not affected by air, water and other natural factors like silver, gold, platinum, generally occur in a free state. The compounds of metals that occur in nature along with the impurities are called minerals.
- What are ores?
- Which processes are involved in the branch of metallurgy? What is metallurgy?
- Which metals are found in a free state?
- In what forms are metals found in combined state?
- What is gangue?
